In the medical and research fields, there are many clinical situations where it is desired or necessary to stop the passage, flow or transfer of substances within a body tube or conduit by causing an occlusion or blockage. It is often desirable for the occlusion to be re-opened at a later time. Unfortunately, many occlusion techniques are often harmful or potentially harmful and are not reversible to accommodate changes in the needs or desires of patients.
One area that has a need for reversible occlusion of a body tube is the control of fertility. Over the last 50 years, the world has experienced the highest rates of population growth and the largest annual population increases recorded in history. Women account for over 50% of the world's population and play a critical role in family health, nutrition, and welfare. One of the most significant areas in need of attention and innovation in women's healthcare is that of contraception, where the reproductive aged woman is currently faced with sub-optimal alternatives.
Over the past 20 years, couples in every world region have adopted contraception with increasing frequency as a means of regulating the timing and number of children. However, in the less developed countries there are still a substantial number of women, who wish to control fertility but are not presently using contraception. Many governments worldwide are intervening with policies to provide access to contraceptive methods to control over-population. In 2000, it was estimated that 123 million women did not have access to safe and effective means of contraception. Therefore, the potential for a suitable contraceptive system has widespread implications for the world population.
Today there are several contraceptive options available, although currently available options are associated with specific limitations. Some contraceptive options include surgical intervention, such as tubal ligation for female sterilization and vasectomy for male sterilization, both of which are invasive and considered non-reversible. Other options available to women are hormonal contraceptives, which are not suitable or safe for a number of women. Further options include intrauterine devices that may have significant side effects. The ideal contraceptive system is one that would provide an immediately effective, reversible, non-hormonal, non-surgical, easy to deliver, office-based solution that does not require anesthesia, patient compliance, or special equipment, and does not leave a foreign body in place long-term. None of the current options meets these requirements.
The most widely utilized method of permanent contraception is tubal ligation or female surgical sterilization. There are a number of major drawbacks associated with tubal ligation. The procedure is permanent and invasive, requires general anesthesia, has a long recovery time, and can result in post-tubal ligation syndrome. Post-tubal ligation syndrome occurs when the surgeon closing the fallopian tube inadvertently damages or destroys blood vessels to the ovaries causing post-menopausal symptoms of abnormal bleeding, memory loss, confusion, mood swings, and lack of sex drive. In addition, a recent study has found that of all the hormonal and non-hormonal methods of birth control, tubal sterilization has the greatest association with development of functional ovarian cysts. Further, women who undergo tubal ligation frequently express regret or seek reversal. Reversal of tubal ligation, when attempted, is difficult, costly, and frequently unsuccessful.
On the other end of the spectrum, the most widely utilized method of non-surgical contraception is the administration of hormonal drugs, such as implanted hormones or birth control pills. This method of contraception is effective only so long as hormones are administered or birth control pills taken according to a specific regimen. Although widely used, this method of contraception is not suitable or safe for all women. In addition, there is a high failure rate resulting in unintended pregnancies due to patient non-compliance with the daily regimen of taking pills.
One reversible contraceptive device currently available is the intrauterine device (IUD). There are an estimated 85 to 100 million women worldwide using this method, substantiating the importance of reversibility. However, given the possible health risks associated with IUDs and patient reluctance to have a foreign body in place for an extended period of time, fewer than 1 million women in the U.S. use this method, and many manufacturers have ceased distribution of these devices. The health risks include unplanned expulsion requiring removal due to excessive pain or bleeding, pelvic-inflammatory disease, permanent infertility, ectopic pregnancy, miscarriage and even death.
While the currently available compositions and methods for contraception represent a significant advancement in the art, further improvements would be desirable to provide safe, effective and reversible non-surgical devices, compositions, and methods for preventing pregnancy. It would be beneficial if these devices, compositions and methods provided an immediately effective, non-hormonal, non-surgical, easy to deliver, office-based solution that did not require anesthesia or patient compliance with a daily regimen. It would be further beneficial if these devices, compositions and methods did not require special equipment to undertake a contraceptive procedure or require a foreign body remaining in place over a long period of time. It would be further beneficial if these devices, compositions and methods were suitable to reversal. Some or all of these advantages of an ideal contraceptive system are provided by the devices, systems, compositions and methods of the present invention.